Organofunctional silanes have been used in latex sealant formulations as adhesion promoters. Among these applications, U.S. Pat. No. 4,626,567 to Chang teaches the use of 0.3-1% of organoaminosilane in acrylic latex based sealant formulations. Applications of organoaminosilane additives have been limited to filled and colored sealants because of the tendency of the organoaminosilane to exhibit yellowing. Non-amino containing organofunctional silanes, such as epoxysilanes, are used instead in both acrylic latex based coatings and sealants. Many efforts have been made to develop epoxysilanes as crosslinkers in the waterborne coating applications. For example, WO 9,531,512-A1 to Padget details a modified epoxysilane for more effective crosslink reaction in coating applications. Japanese patent publication JP 01174560A2 to Kimura for solvent based sealant applications, states that epoxysilane can provide polyamide based sealants with high extensibility, low modulus, and excellent adhesion to substrates.
Currently, glycidoxypropyltrimethoxysilane is used in formulations, but it suffers from several limitations. Among these are that it provides incomplete adhesion under wet conditions, especially to glass; its shelf life is short, and its adhesion properties disappear upon storage of the composition.